We have a new endpoint available for the Engagements API that will let you get recently created or updated engagements. The endpoint can be used to poll for new or updated engagements, allowing you to sync new or modified notes, sales emails, calls, tasks, and other sales activities from HubSpot.

@Paul_Cannon engagements are used for most sales activities, so this would include notes being added to records, emails sent to a contact from the contact record view (this would not include marketing emails sent to lists), calls, activities, tasks, or meetings scheduled with contacts.